Updating information regarding sections of a streamer that are in a body of water

ABSTRACT

To perform a marine survey, a streamer is deployed into a body of water, where the streamer has plural first sensors to perform a subterranean survey. Indications are received from second sensors in corresponding sections of the streamer, where the indications are regarding which sections are in the body of water. Information is updated regarding which sections of the streamer are in the body of water in response to the received indications.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 11/737,627, U.S.Patent Publication No. 2008/0262738, filed Apr. 19, 2007, now U.S. Pat.No. 8,060,314 entitled “UPDATING INFORMATION REGARDING SECTIONS OF ASTREAMER THAT ARE IN A BODY OF WATER,” which is hereby incorporated byreference.

TECHNICAL FIELD

The information relates generally to performing a marine survey thatincludes updating information regarding which sections of a streamer arein a body of water.

BACKGROUND

Each of a marine seismic streamer and seabed cable is an elongatecable-like structure, which can be several thousands of meters long. Thestreamer or cable includes arrays of acoustic sensors (e.g.,hydrophones) and associated electronic equipment along the length of thestreamer. The acoustic sensors are used to perform marine and seabedseismic surveying.

Typically, a number of streamers are towed by a sea vessel to perform amarine seismic survey, while a seabed cable is deployed from the seavessel and laid on the sea floor. The streamers and seabed cables aredeployed from the sea vessel, typically from the aft of the sea vessel.Each streamer or cable is unwound from a reel or spool for deploymentinto the water. As a streamer or cable is deployed, it is useful todetermine which sections of the streamer or cable are in the body ofwater. Typically, this is accomplished by using RFID (radio frequencyidentifier) readers positioned on the aft deck to detect RFID tags onthe sections that are being deployed.

An issue associated with using this mechanism to detect which sectionsof the streamer are in the water is that there is typically a lot ofactivity at the aft desk of a sea vessel. Such activity may damage theRFID reader, such as due to accidental impact of other equipment withthe RFID reader.

Another issue associated with using an RFID reader to read tags on thestreamer or cable is that the RFID reader has to be far enough away fromthe streamer/cable reel and other sections of the streamer or cable toensure that the RFID reader only detects the section that is beingdeployed. Such a requirement places constraints on the building of anRFID deployment system.

SUMMARY

In general, according to an embodiment, a method of performing a marinesurvey includes deploying, into a body of water, a streamer havingplural first sensors for performing a subterranean survey, andreceiving, from second sensors in corresponding sections of thestreamer, indications regarding which sections are in the body of water.Information regarding which sections of the streamer are in the body ofwater is updated in response to the received indications.

Other or alternative features will become apparent from the followingdescription, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a sea vessel that deploys multiple streamers,according to an example.

FIG. 2 illustrates a portion of the streamer, according to an exampleembodiment.

FIG. 3 is a block diagram of a control system, according to anembodiment.

FIG. 4 is a flow diagram of a process performed by the control system ofFIG. 3, according to an embodiment.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments are possible.

FIG. 1 illustrates a sea vessel 100 that has a reel or spool 104 fordeploying a streamer 102, which is a cable-like structure having anumber of sensors 103 for performing a subterranean survey of asubterranean structure 114 below a sea floor 112. A portion of thestreamer 102, and more particularly, the sensors 103, are deployed in abody of water 108 underneath a sea surface 110. The streamer 102 istowed by the sea vessel 100 during a seismic operation. In analternative implementation, instead of using a streamer that is towed inthe water by the sea vessel 100, a seabed cable can be used instead,where the seabed cable is deployed from a reel on the sea vessel andlaid on a sea floor 112. In the following, the term “streamer” isintended to cover either a streamer that is towed by a sea vessel or aseabed cable laid on the sea floor 112.

Also depicted in FIG. 1 are a number of signal sources 105 that producesignals propagated into the body of water 108 and into the subterraneanstructure 114. The signals are reflected from layers in the subterraneanstructure 114, including a resistive body 116 that can be any one of ahydrocarbon-containing reservoir, a fresh water aquifer, an injectionzone, and so forth. Signals reflected from the resistive body 116 arepropagated upwardly toward the sensors 103 for detection by the sensors.Measurement data is collected by the sensors 103, which can store themeasurement data and/or transmit the measurement data back to a controlsystem 106 on the sea vessel 100.

The sensors 103 can be seismic sensors, which are implemented withacoustic sensors such as hydrophones or geophones. The signal sources105 can be seismic sources, such as air guns or explosives. In analternative implementation, the sensors 103 can be electromagnetic (EM)sensors 103, and the signal sources 105 can be EM sources that generateEM waves that are propagated into the subterranean structure 114.

Although not shown in FIG. 1, the streamer 102 further includesadditional sensors (e.g., depth sensors), which are used to detect aposition of respective sections of the streamer 102. In accordance withsome embodiments, data from these additional sensors are sent back tothe control system 106 to allow the control system 106 to updateinformation regarding which sections of the streamer 102 are in the bodyof water 108, and which sections of the streamer 102 are outside thebody of water.

FIG. 2 shows a portion of the streamer 102, including sections 200A,200B, and 200C. The section 200A includes a corresponding sensor 103(such as a seismic sensor) for detecting subterranean features. Thesensor 103 can be deployed once every few sections of the streamer 102in one example. Alternatively, each section can have a correspondingsensor 103 for detecting subterranean features.

In the ensuing discussion, reference is made to seismic sensors. Note,however, in other implementations, the sensors used for detectingsubterranean features can be EM sensors. Note also that the arrangementin FIG. 2 is an example arrangement. Different arrangements can be usedin other implementations. The streamer 102 includes additional equipmentthat is not shown in FIG. 2.

The section 200A further includes a second sensor 202A, which in someembodiments is a depth sensor to detect the depth of the section of thestreamer 102 in the body of water 108. Each of the other sections 200B,200C depicted in FIG. 2 also includes a corresponding second sensor202B, 202C (e.g., depth sensors).

The section 200A further includes a steering device 204 to help steerthe streamer 102 in the body of water. The steering device 204 caninclude control surfaces 206 (in the form of blades or wings) that arerotatable about a longitudinal axis of the streamer 102 to help steerthe streamer 102 in a desired lateral direction. The steering device 204can be provided once every few sections of the streamer 102.

In some implementations, the steering device 204 includes a battery (orother power source) 208 that is used to power the steering device 204.The battery 208 can also be used to power the depth sensor 202A in thesection 200A, as well as depth sensors 202B, 202C in other sections200B, 200C that are relatively close to the section 200A containing thesteering device 204. Power from the battery 208 is provided overelectrical conductor(s) 210 to the depth sensors 202A, 202B, 202C. Inalternative implementations, power can be provided from an alternativesource, such as from the sea vessel 100 over an electrical cable 212 (orfiber optic cable) that is routed through the streamer 102. To derivepower from a fiber optic cable, each sensor 202 would include aconversion circuit to convert optical waves into electrical power.

In accordance with some embodiments, the depth sensors 202 (202A, 202B,202C shown) are used to detect which sections 200 of the streamer 102are deployed in the body of water 108. The depth sensors 202 providedata regarding whether corresponding sections are in the body of water108 by communicating the data over a communications link (e.g.,electrical or fiber optic cable) 212 that is run along the length of thestreamer 102 to the reel 104 on the sea vessel 100. The data providedfrom the depth sensors 202 are received by the control system 106.

Based on the data provided by the depth sensors 202, the control system106 is able to update information regarding which sections of thestreamer 102 are deployed in the body of water 108 and which sections ofthe streamer 102 are outside the body of water 108. The control system106 is able to update a visual representation of a spread in response tothe received data. Note that the visual representation of the spread isupdated continually as information is continually received from thedepth sensors 202. A spread refers to an arrangement of seismic sensorsdeployed in the body of water 108 to perform a seismic survey. A spreadtypically includes a number of streamers.

As streamer sections are powered up after the depth sensor detects thatthey are in the water, the positioning system will be enabled. Typicallythrough a transformation of measurement information (including GPSantenna equipped floats, acoustic transmitters and receivers, andcompasses providing directions) to the position domain, the deployedstreamer sections can be visualized with a fairly accurate spatialrelation. Coordinate estimates of points along the streamer are used toguide the streamer steering devices.

The visual representation of the spread can be in the form of a map orother diagram that includes icon elements representing respectivesections (and sensors) of the streamers. Some indicator can beassociated with each section in the visual representation to indicatewhether or not the particular section is in the body of water 108. Theindicator can be in the form of text, an icon, or a different color(e.g., red to indicate out of water and green to indicate in water). Theindicator can have a first state to indicate that the respective sectionis in the water, and a second state to indicate that the respectivesection is out of the water. The visual representation can be in theform of a graphical user interface (GUI) screen. Alternatively, thevisual representation can be in text format that lists which sections ofwhich streamers are in water and which are not in water.

Based on the information contained in the updated visual representationof the spread, an operator on the sea vessel 100 can perform operationswith respect to the sections of the streamers. For example, it isdesirable that sections of a streamer that are outside the body of water108 not be powered when the streamer 102 is being deployed into thewater (to avoid over-heating problems). Thus, the operator can disablepower to sections of the streamer that are indicated by the visualrepresentation as being outside the body of water 108, and to activatepower to equipment in the sections of the streamer that are indicated tobe inside the body of water 108. The operator can activate/deactivatecontrol elements of a GUI provided by the control system 106 toactivate/disable power to equipment in the sections of the streamer 102.Alternatively, the control system 106 can include actual physicalbuttons that are actuated by the operator to control power to thesections of the streamer 102.

Among the equipment powered are steering devices 204, which are used tonavigate the streamer 102. Activating power to equipment in a section ofthe streamer refers to activating power to equipment other than thedepth sensor (since the depth sensor) has to be activated to allow forindications to be communicated to the control system 106 to indicatewhether or not a particular section is in the body of water 108.

Data pertaining to whether or not particular sections of the streamerare in or out of the water can also be used in the reverse direction,when the streamer 102 is being retrieved from the body of water 108.This information helps the operator determine which sections are to bepowered off and which sections are to remain activated.

The depth sensors 202 are thus used for a dual purpose: (1) to detect adepth of sections of the streamer 102 during normal operation (e.g., aseismic survey operation); and (2) to detect sections that are in thebody of water 108 so that such sections can be powered.

FIG. 3 is a block diagram of an example arrangement of the controlsystem 106. The control system 106 includes spread visualization andcontrol software 300 that is executable on one or more centralprocessing units (CPUs) 302. The spread visualization and controlsoftware 300 controls the display of a spread diagram 303 in a displaydevice 306. The spread diagram 303 can be in the form of a GUI screen tovisually display GUI elements representing sections of the streamers ofa particular spread.

The CPU(s) 302 is (are) connected to a storage 304 and a communicationsinterface 305 to communicate with the communications link of thestreamer 102.

An operator can also use the spread visualization and control software300 to control activation and disabling of power to sections of astreamer. The operator can perform the power activation and disablingusing GUI control elements displayed in the display device 306, or usingactual physical control buttons.

FIG. 4 is a flow diagram of a process performed by the control system106 according to an embodiment. As a streamer 102 is being deployed fromthe sea vessel 100 into the body of water 108 (or being retrieved fromthe body of water 108 back onto the reel 104), the control system 106receives (at 402) indications from depth sensors 202 in the streamersections. The indications can be received on a periodic basis. Thevisual representation of the spread is updated (at 404) in response tothe received depth sensors. The visual representation of the spread isupdated to indicate which streamer sections are in the body of water 108and which streamer sections are outside of the body of water 108.

The sections of the streamer are then activated or disabled (at 406)according to the updated visual representation. Note that althoughreference has been made to an operator activating or disabling sectionsof the streamer based on the visual representation, it is noted that thecontrol system 106 can automatically disable or activate sections of thestreamer based on information from the depth sensors indicating whetheror not the particular sections are in the body of water.

Instructions of software described above (including spread visualizationand control software 300 of FIG. 3) are loaded for execution on aprocessor (such as one or more CPUs 302 in FIG. 3). The processorincludes microprocessors, microcontrollers, processor modules orsubsystems (including one or more microprocessors or microcontrollers),or other control or computing devices. A “processor” can refer to asingle component or to plural components.

Data and instructions (of the software) are stored in respective storagedevices, which are implemented as one or more computer-readable orcomputer-usable storage media. The storage media include different formsof memory including semiconductor memory devices such as dynamic orstatic random access memories (DRAMs or SRAMs), erasable andprogrammable read-only memories (EPROMs), electrically erasable andprogrammable read-only memories (EEPROMs) and flash memories; magneticdisks such as fixed, floppy and removable disks; other magnetic mediaincluding tape; and optical media such as compact disks (CDs) or digitalvideo disks (DVDs).

While the invention has been disclosed with respect to a limited numberof embodiments, those skilled in the art, having the benefit of thisdisclosure, will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover suchmodifications and variations as fall within the true spirit and scope ofthe invention.

1. A method of performing a marine survey, comprising: deploying, into abody of water, a streamer having plural first sensors for performing asubterranean survey; receiving, from second sensors in correspondingsections of the streamer, indications regarding which sections are inthe body of water; updating information regarding which sections of thestreamer are in the body of water and which other sections of thestreamer are outside the body of water, in response to the receivedindications; providing, by a control system based on the updatedinformation, power to activate equipment in the sections of the streamerin the body of water; and disabling, by the control system based on theupdated information, power to equipment in the sections of the streameroutside the body of water.
 2. The method of claim 1, wherein updatingthe information comprises updating a visual representation of a spreadincluding the streamer.
 3. The method of claim 2, wherein updating thevisual representation of the spread comprises updating displayedindicators of which sections of the streamer are in the body of waterand which sections of the streamer are outside the body of water.
 4. Themethod of claim 3, wherein the spread further comprises at least anotherstreamer having first sensors for performing a subterranean survey, andsecond sensors, the method further comprising: receiving indicationsfrom the second sensors of the at least another streamer regarding whichsections of the at least another streamer are in the body of water; andupdating the visual representation of the spread in response to thereceived indications from the second sensors of the at least anotherstreamer.
 5. The method of claim 1, wherein providing power to activatethe equipment in the sections of the streamer in the body of watercomprises providing power to activate one or more steering devices inthe streamer.
 6. The method of claim 1, wherein receiving theindications from the second sensors comprises receiving the indicationsfrom depth sensors.
 7. The method of claim 1, wherein deploying thestreamer having the plural first sensors comprises deploying thestreamer having plural acoustic sensors.
 8. The method of claim 1,wherein deploying the streamer having the plural first sensors comprisesdeploying the streamer having plural seismic sensors.
 9. The method ofclaim 1, wherein deploying the streamer having the plural first sensorscomprises deploying the streamer having plural electromagnetic sensors.10. The method of claim 1, further comprising: retrieving the streamerfrom the body of water onto a reel, wherein receiving the indicationsfrom the second sensors and updating the information is performed alsoduring retrieving of the streamer.
 11. The method of claim 1, whereinthe indications are received from the second sensors on a periodicbasis, and wherein the information regarding which sections are in thebody of water and which sections are outside the body of water isupdated repeatedly with the periodic receptions of the indications fromthe second sensors.
 12. The method of claim 1, wherein deploying thestreamer comprises deploying the streamer towed by a sea vessel.
 13. Themethod of claim 1, wherein deploying the streamer comprises deploying aseabed cable laid on a sea floor.
 14. A control system to controldeployment of a streamer into a body of water, comprising: a processorto: receive data from sensors in the streamer that contains equipment toperform a subterranean survey; update information regarding whichsections of the streamer are in the body of water and which sections ofthe streamer are outside the body of water; cause provision of power toactivate equipment in the sections of the streamer in the body of wateraccording to the updated information; and cause disabling of power toequipment in the sections of the streamer outside the body of wateraccording to the updated information.
 15. The control system of claim14, wherein the received data from the sensors comprises data from depthsensors.
 16. The control system of claim 14, further comprising: adisplay device to present a visual representation of the sections of thestreamer.
 17. The control system of claim 16, wherein the visualrepresentation of the sections of the streamer contains representationsof one of seismic sensors and electromagnetic sensors for performing thesubterranean survey.
 18. An article comprising at least onenon-transitory computer-readable storage medium storing instructionsthat when executed cause a computer to: receive data from sensors in astreamer that contains equipment to perform a subterranean survey;update information regarding which sections of the streamer are in abody of water and which sections of the streamer are outside the body ofwater; cause provision of power to activate equipment in the sections ofthe streamer in the body of water according to the updated information;and cause disabling of power to equipment in the sections of thestreamer outside the body of water according to the updated information.19. The article of claim 18, wherein the instructions when executedcause the computer to further display control elements in a visualrepresentation of the streamer to allow user input for activating anddisabling power to respective sections of the streamer.